DE19835041C1 - Monitoring arrangement for wheel processes on high speed rail vehicles - Google Patents

Abstract

the arrangement has pulse generators mounted on the wheels or wheel sets for generating a pulse sequence dependent on the wheel revolution rate. Transducer elements are distributed uniformly on the wheel body or rim if fitted, or sensors can be fixed to the vehicle frame opposite the wheel. The gaps between the pulses are filed with pulses from a higher frequency clock generator and the resulting clock pulse sums related to the current speed or revolution rate are used by a processor in direct digital form as a reference comparison value for monitoring the wheel processes

Description

The malfunctions of the wheel drains that endanger safety is known to occur practically unavoidably while driving, to the extent that they have not yet been detected by means of signaling, first of all a more detailed description of the causal relationships:

In the first place are:

The insufficient or already canceled lane keeping over the lateral lane rim of the wheel to the rail with direct risk of derailment, caused by for example due to defective or incorrect setting of the course.

Then, for special wheel designs:

For example, an offset slip of the wheel tire on the actual wheel body as a result Tension or friction loss between the joining surfaces (shrinking) due to material fatigue, which is also caused in connection with operational vibrations can be seen.

However, undetected production errors can also be responsible for this be that the finest hairline cracks spread in the wheel tire and affect the strength pregnant.

An offset slip of the wheel tire would therefore always be a serious indication for you represent possible serious wheel drain defect.

Furthermore:

Bearing defects, sometimes resulting in overheating with beginning wheel blockages may have with at first only sporadically and very briefly occurring Delays of the wheel run through to the complete slipping of the wheel the rail, so that it may spontaneously turn into a while driving Can develop a crack in the tread, with an acute risk of breakage and detachment of the wheel tire itself.

Blocking of the wheel arch or sliding of the wheel arch on the Rail at risk of derailment are brought about by stops on Web body, for example by means of so-called on the rails Inhibitors, but also by much more.

These are some of the most important causes of malfunctions in the wheel sequences, which can just happen while driving, always express themselves with one corresponding, mechanically and physically related change in wheel speed. As an announcement of a possible actual defect, this can only be extreme for a short time, and therefore only at certain points, in the course of one revolution in Appearance.

An appropriate monitoring system should therefore ensure that each Axle and drive wheel already with an impending wheel drain defect initially not yet serious wheel speed change, by means of a suitable  and therefore senses highly sensitive sensors and for evaluating a computer control that weighs the necessary measures, including for one possibly still possible "moderate" onward journey.

In any case, a special premise of the independence of the control system from the rest of the logistics management, because a detected error in the "Apron" of a possibly serious defect, immediately following not any control over a perhaps still limited speed should exclude permissible onward travel.

This also includes the ability to report a defect and possible "moderate" onward journey, also one via the identical wheel sensor system another, or the same, but possibly progressive defect, is nevertheless able to grasp.

Therefore, there should be none on the wheel sensor system after the relevant defect message subsequent mechanical readjustment may be necessary, which is therefore certainly also would question the compatibility with a higher-level logistics control system.

Considered - state of the art

In this regard, there are proposed solutions for monitoring the wheel tires known, the magnet with fixed set on the same radius switch sensors (permanent magnets) on the wheel body and on the wheel tire work, depending on the simultaneous passing of on the chassis against Overlying electronic magnetic switch (sensor), so that already after the slightest slip offset between the wheel tire and the wheel body, the signal message can be triggered, but then afterwards workshop-based readjustment measures would have to be taken, for example, for the "moderate" Continuing to allow another error message from the same bike.

In addition, there is the disadvantage of a rather one-sided and not comprehensive application Possibility of application, which only refers to the slip between wheel tires and Refers to the wheel center.

The following are also known:

Devices with speed-dependent electronic pulse generation based on a rotating circumferential circle have encoder segments with constant pitch that a stationary electronic sensor (Hall effect Actuate sensor, inductor sensor) without contact.

This is comparable to actuation by tooth head as well as by Tooth gap of a gear - as a plus / minus signal, so that a Processor from the changing pulse train, for example a normal one or maximum braking acceleration from one that is according to one of the above-mentioned wheel drain defects results, could almost distinguish.  

However, this method has the disadvantage of being elementary, relative low resolution, which is causal from the direct sequence or proportionality which gives impulses with the speed-dependent rotation of the encoder segments.

In practice, this could have the effect that relatively small, selective or partial slipping of a wheel is insufficient, even with a time delay and therefore not current, can be detected.

This relatively late, moreover, also insensitive response, for example in the first Moment of the wheel arch disorder, therefore brings certain restrictions for optimal wheel arch control by using the previously described Interference effects are not already in the so-called "apron" of a serious Defect can be comprehensively and currently recognized.

From automotive safety technology, for example for anti-lock controls (ABS systems), the measurement value acquisition for the wheel speed changes is known, the higher frequency-dependent pulses in analog voltages by means of Generated so-called digital-analog converter for brake control.

There are positive and negative, modified square half-waves generated, belonging to the course of the tooth head and that of the tooth gap, the "1" and "0" pulse intervals alternately formed by the sensor are a measure of time for the number of higher-frequency oscillator pulses to be recorded represent, and consequently a speed-dependent measured value AC voltage for the regulation.

In the document DE 25 53 806 A1 a system is set out in the previous the sense described should also serve the ABS regulation:

Two oscillators are then used, assigned separately, for the Tooth head as well as for the tooth gap.

This assignment is done only for the necessary compensation of the two oscillators, due to width differences that exist in practice between tooth tip and tooth gap, caused by tool norms, which also in the manufacturing z. B. from profile or spline shafts of automotive engineering find broad application.

By including the tooth gap in the acquisition process, Increasing the resolution can be effected.

To make this possible, at the beginning of the process after the Has set the vehicle in motion, the oscillator pulses above the tooth tip and The course of the gaps was counted, saved and separately using a period counter fed to a comparator, after which a comparison the corresponding correction or Tuning the frequency for the tooth gap has the result, so that more and more Operation can be set accordingly.  

In the patent specification DE 195 24 358 C1, "hazard warning light device on motor vehicles testify with selectively adapted automatic triggering primarily for selection a panic braking ", a circuit or pulse processing system for Evaluation of braking decelerations and the detection of wheel speed changes proposed.

There are several rotary encoders on the wheels or drive axles (several stationary sensors and only one rotating encoder segment or alternatively, several rotating encoder segments and only one stationary sensor) circumferentially equally spaced and operated according to vehicle speed.

The intervals resulting from the successive impulses become with Clock pulses of a higher-frequency clock generator (oscillator) filled up. It can therefore be in the processor according to the abrupt full braking lengthening intervals the correspondingly increasing numerical values be classified, with diverse application, for example also to algorithms for complex control and regulation processes;

in the present application for the most realistic selection possible beginning "panic braking" to a hazard warning lights system automatically turn on.

The publication DE 198 00 607 A1, "Control device for wheel speed changes to motor vehicles " a further design and possible variation in the applications of this Impulse system to the content by increasing the number significantly the encoder segments and adjusted accordingly, the clock frequency for filling the pulse intervals can be carried out to an extraordinary extent. This should open up new perspectives for the further development of ABS / ASR rule systems, etc. can be seen, as well as a combined application to signal a sudden onset of critical tire pressure loss Motor vehicles (tire condition detection) while driving.

For this purpose, one is also likely in claim 3 of this document more powerful sensors described on the rotating encoder side permanent magnetic pulse generator segments in corresponding circumferential continuous division, which is also integrated there in the manufacturing process can be permanently magnetized, and all are aligned in the same polarity - and on the stationary sensor side, designed as a piezo quartz sensor, which in its outer structure is based on the piezo quartz arrangement (single or serial position) permanent magnetic applied under the required static preload Closing element that is due to the pole orientation of the same name to the opposite encoder segments a repulsive pressure effect as a result with a correspondingly small air gap on the piezo quartz arrangement, so that a total of exactly in terms of amplitude shape and timing reproducible voltage signal as a usable switching pulse to form the Intervals can be generated.  

Patent 31 31 352 C2 also shows in this context Different versions of a piezo quartz sensor, but in contrast to the above-mentioned embodiment deflectable by the actuating force Piezo quartz plates have, and do not have the feature that a Piezo quartz arrangement is present under a defined static bias. This means that the housing is completely fixed and braced on the front the actuating force non-deflectable plate arrangement, with electrodes and Insulation layers that also have the permanent magnetic added above them Include the end element (actuator).

This different structure has a significantly different characteristic of the Impulse generation and possible applications.

The present invention has for its object a comprehensive Monitoring system for the wheel drains on high-speed rail travel testify to suggest that the most essential and most serious malfunctions of the wheel sequences instantaneously and thus can capture highly sensitive.

Furthermore, it should be possible to connect further solutions that the increasing safety requirements of a high speed rail traffic justice, especially by providing maximum compatibility as well Flexibility is guaranteed, like this only with software-controlled processor Applications seems feasible.

This object is solved by the features of claim 1.

Embodiment - advantages of the invention

The circuit or pulse processing described in the prior art system for evaluating braking decelerations and the associated Acquisition of wheel speed changes on motor vehicles offers comprehensive A solution to the problem at hand as well as a specific task Application with effective effects:

A certain number to be determined empirically and circumferentially equally spaced Pulse generator (segments), but rather separate for this special version placed on a suitable circumference or the side of the wheel tire and for rail operations larger and more robust encoder elements operate one without contact sensor sensors attached to the chassis, for example, form in Depending on the rotation of the wheel (wheel set) corresponding time sequences the pulse intervals, each with the higher-frequency pulses of the quartz clocked and thus constant timeline (pulse generator / oscillator) with a certain number of clock pulses added to a relevant total number be replenished.  

The resulting number chains that are continuously displayed in the processor especially in contrast to pneumatic tires for motor vehicles - because they are more constant There is a metallic wheel circumference - also as a numerical value for the current one Assign interval related to a very specific speed parameter are saved (buffer / ring buffer) as long as they are quasi continuous evaluation or monitoring required.

So that the corresponding reference comparisons among the relevant wheel are runs (wheel sets) of a chassis group with the highest resolution and accuracy ability to produce, which is included in the direct digital comparison of numerical values tolerance deviations that occur normally, current statements for a Allow starting wheel drain defect.

With an appropriate design, it becomes obvious that the slightest slippage or resulting wheel speed changes are sufficient, even a sudden one limited slip offset of a wheel tire with relative change in wheel speed, a differentiable reference statement about the processor with corresponding Get software.

This obviously also includes the current recording of the moment of the Derailment, which always with one, although initially only slight Wheel speed change goes hand in hand, and over this numerical value reference comparison, for example within a wheel group, can be signaled very early. In terms of signaling, this also gives the processor the ability to: identify individual affected wheel.

As a prerequisite, it can certainly be assumed that under the Assumption of a sufficient number not all at the quasi-continuous Reference comparison involved wheels at the same moment the identical fault Statistically seen history, so that with special software secure Differentiation statements can be made.

This may result in the influence of these high speeds also "normal", creeping and slight wheel speed fluctuations within the Comparison wheel groups, such as when crossing points or cornering, so that here too, with the appropriate software, there is certainly an existing characteristic to differentiate these fluctuations with the "real" wheel drain defects will be.

This direct and software-controlled, exclusively in the processor Comparison method offers the considerable advantage of being significantly increased Possibilities of a highly sensitive resolution and flexibility, for example too with possible application of complex algorithms, each on a single one as well as the smallest angle segment (min. encoder distance) of the running wheel circumference based.  

With this in mind, even with a sudden and limited slip offset of a wheel tire record and evaluate the corresponding relative speed change leave, but without a subsequent readjustment in order to renew to be able to record related error messages while driving.

The sensor sensor elements must therefore be used in a version with wheel tires attached to itself to detect the relative speed change or be made integrated.

At the available speeds, up to 350 km / h, for the Wheel sensors under this application have the highest requirements for maximum Switching frequency and reproducibility of the pulse signals in order to be effective and to achieve safe functioning.

The state of the art mentioned will probably be more powerful and less sensitive variant of the pulse generation on the basis of the piezoelectric effect presented and proposed. In contrast to this, the sensors used are known to work up inductive base, with signaling under metallic approach; or accordingly, those are also known which, using the Hall Effect (magnetic field changes) generate switching signals.

In this piezoelectric variant, the rotating ones permanent magnetic encoder segments, all in constant polarity are aligned, the stationary under the pole orientation of the same name Piezo quartz sensor located opposite and with a small air gap pass and apply slight (repulsive) pressure effects.

According to the invention, the alternative is now also available as a supplement proposed the following modified method, which is robust Operation for rail vehicles, in particular for reasons of operating and Environmental conditions, should be more fair:

For this purpose, the encoder elements rotating with the wheel are not permanently magnetized netisch executed, but consist of appropriately remagnetisable Material.

Special steel may be sufficient, so that these donor elements are likely to be used e.g. B. cast on and on the wheel flank or on the wheel tire flank can be edited accordingly.

With rotation, they become each when they pass the piezo quartz sensor static preload impulsed and dynamically superimposed as a result of the Relieve magnetization (correspondingly small air gap with approx. 3 ÷ 5 mm assuming), since the applied under static prestressing and in Sensor head integrated permanent magnetic termination element (actuator) each a relative pull effect on the piezo quartz arrangement (single or series position)  is exercised so that an electronically amplified signal, for example in reverse electrical polarity.

Voltage differences that occur, both electrical and mechanical, for example caused by temperature fluctuations as well as by manufacturing tolerances are therefore due to the superimposed dynamic pulse generation of of no importance and can also be easily compensated for.

Claims (4)

1. Control device for wheel drains on high-speed rail vehicles with provided on the wheels or the wheel sets pulse generators for generating a wheel speed-dependent pulse train, characterized in that a circumferentially equally spaced number of transmitter elements are arranged on the wheel bodies or, when running with wheel tires on the wheel tires , alternatively also on the corresponding wheel sets, which, depending on the speed or the peripheral speed of the wheel tread, actuate stationary sensors located opposite one another on the chassis, that the intervals formed by the successive pulses are filled with clock pulses from a higher-frequency clock generator, so that the generated thereby on the current speed or speed-related clock pulse sum of an interval as a numerical value is used directly digitally by the processor as a reference comparison value for checking the wheel sequences with one another. 2. Control device according to claim 1, characterized in that that given by the speed of travel and quasi continuously determinable number reference values are stored and each from Processor can be accessed or that in each case for the corresponding reference comparison, depending on the current speed, these numerical values from the processor be continuously formed. 3. Control device according to claim 1 and 2, characterized in that the numerical values formed are briefly for each cycle run interval be stored, and the processor as well as a controller related to neighboring or other wheels, wheelsets, as well as others Trolleys, manufactures and incorporates tolerance limits and by means of appropriate software detect an onset wheel defect, differentiate and identify its location. 4. control device, according to the preceding claims, using a piezoelectric sensor system, which uses an im Sensor head on the piezo quartz arrangement under defined static Bias applied permanent magnetic termination element passing a permanent magnetic sensor element physically conditional pressure effect on this arrangement that the piezoelectric Signal voltage generated, the pressure effect due to the opposite eponymous polarity of the magnets under a correspondingly small air gap is caused characterized, that the encoder element consists of a remagnetizable material and by passing on the sensor head that is attached to it permanent magnetic termination element in its defined static Bias due to the onset of magnetization by the triggered Relieved tensile effect, so that the applied with the static preload piezoelectric rest potential the evoked piezoelectric signal in reverse electrical polarity is dynamically superimposed.